Description of Related Art
This image processing apparatus is used to produce clearer pictures from radiography equipment so that a doctor has the information needed for a diagnosis. A known form of this apparatus comprises an image processor in which integrated frames of video information from radiography equipment are stored on discs at a maximum rate of three pictures per second. These input signals are obtained continuously over a period of time, at some point in which a radio-opaque dye is introduced into the patient. Once the dye has passed through the part of the patient which is of interest the recorded pictures can be processed in such a way as to show clearly the part affected by the dye. In order to achieve this two frames of video information are taken from the disc store, one before the dye was introduced and one after, and subtracted. This removes the background and leaves the part with the dye clearly visible. An improvement in the signal-to-noise ratio in the processed pictures can be brought about by taking the sum of the clearest pictures before and after the dye has been introduced and subtracting the two sums, or by summing a continuous sequence using a weighted co-efficient scheme.
One problem with this system is the slow rate of storage on the disc store. This severely limits the amount of information that can be obtained from rapidly moving structures, such as the heart where the local motion of the heart wall is of importance in diagnosis.